U.S. Pat. No. 3,671,241 issued June 20, 1972 discloses and claims image-receiving elements which comprise an image-receiving stratum composed of a silver precipitating agent dispersed therein, the image-receiving stratum having been rendered "permeable" to an alkaline processing composition by suitable modification prior to photographic processing but after the silver precipitating agent has been incorporated. In the most useful embodiments, the image-receiving stratum comprises regenerated cellulose obtained by alkaline hydrolysis of a cellulose ester, e.g., cellulose diacetate, and containing a silver precipitating agent. As disclosed in said patent only a depthwise portion of the cellulose ester stratum need be hydrolyzed to regenerated cellulose. The transferred silver is precipitated within the regenerated cellulose stratum thus obtained, even though an additional depthwise portion of the cellulose ester may be hydrolyzed to cellulose during the diffusion transfer process and additional silver precipitating nuclei thus made available.
U.S. Pat. No. 3,607,269 issued Sept. 21, 1971 discloses and claims improvements in image-receiving elements of the type disclosed by U.S. Pat. No. 3,671,241 wherein various photographic reagents may be disposed initially in the stratum of unhydrolyzed polymer and extracted from the polymer during processing. The disposal of such reagents and subsequent extraction permits the utilization of compounds which are desirable during processing but which could be detrimental to the process if made available at the wrong time. This makes it possible to utilize a wide variety of photographically useful reagents and to control or meter the rate at which they become available to participate in the process. As with U.S. Pat. No. 3,671,241, the image-receiving elements are prepared by hydrolyzing a depthwise portion of the hydrolyzable polymer layer prior to photographic processing.
U.S. Pat. No. 3,969,541, issued July 13, 1976, is directed to a method for forming a diffusion transfer image-receiving sheet which comprises contacting a surface portion of an alkali impermeable polymer with a solution containing both silver precipitating nuclei and a material capable of hydrolyzing a portion of said polymer. This method simultaneously makes the surface portion of the polymer alkali permeable and incorporates silver precipitating nuclei therein.
U.S. Pat. No. 3,976,817, issued Aug. 24, 1976, is directed to a method for forming a diffusion transfer image-receiving sheet which comprises hydrolyzing the surface portions of an alkali-impermeable polymer and, subsequent to said hydrolysis, absorbing diffusion transfer nuclei into said surface portion from a solution or dispersion of the nuclei in a solvent selected from the group consisting of water, a ketone, an alcohol or a mixture of these solvents.